Various methods are known in the prior art for making absorbent sanitary articles, and in particular for joining separate accessory elements, such as, for example, closing flaps, to the main portion, that is, the absorbent portion (or core) of the article.
It should be noted that, in recent years, the development of the technology has increasingly led to the design of production lines which are able to minimize the waste material which is obtained as a result of the numerous cutting operations performed during processing.
In this regard, numerous patent publications describe processes which, starting from two or more webs of elastic material, make cuts such as to define pieces of web having geometrical shapes which are interpenetrating with alternating orientations.
The pieces can therefore be applied directly to the supporting web (chassis) following suitable rotations or translations, avoiding the production of waste and also allowing the “leg opening” of the absorbent article to be obtained.
For example, patent document EP1941853 describes a method for making absorbent sanitary articles where the flaps are made from a pair of parallel webs of elastic material, which are cut in such a way that each of them is divided into an alternating succession of first and second pieces which are trapezoidal in shape.
More specifically, the pieces of the first web are mirror-symmetrical to the pieces of the second web.
In the first pieces of both the webs, the long bases face each other, whilst in the second pieces, the short bases are facing each other.
In order to apply the flaps in the correct direction (that is, with the long bases facing each other), the method comprises rotating each of the second pieces of both of the webs by 180° so as to obtain an ordered succession of pairs of pieces having the same orientation, such as to allow a direct application of the pieces, that is to say, the flaps, to the continuous supporting web.
Another solution is known from patent document EP1994919, where the two webs are cut in an equivalent fashion, not mirror-symmetrical, that is to say, in such a way that each short base of a piece of the first web faces the long base of a corresponding piece of the second web.
In other words, each web has a plurality of first pieces, whose long base is oriented towards the other web, and a plurality of second pieces, whose short base is oriented towards the other web.
In order to obtain a correct orientation of the flaps, the method comprises a step of rotating all the second pieces of both webs, which unlike the method described above are alternating, but which, once rotated, similarly define an ordered succession of pairs of pieces having the same orientation.
Disadvantageously, these methods are difficult to implement in the production of nappies for adults, in which the size of the flaps (or pieces) prevents handling and positioning in the “traditional” manner.
Moreover, it should be noted that the methods in question require the flaps to be positioned and fixed directly on the outside face of the chassis, by gluing or other similar processes, in order to guarantee that the flaps maintain their position even after a pulling action (that is, in use).